Information storage apparatus including an uniterruptible power supply (UPS) and an interlock control method of the same, comprising

ABSTRACT

In an information storage apparatus including an uninterruptible power supply (UPS), a sequence of operation from when a power failure occurs to when power of the UPS is turned off is automatically accomplished completely without human power to thereby guarantee user data. For this purpose, the apparatus includes a disk array, a host, and a plurality of UPSs to supply power to the disk array and the host. The UPSs monitor a state change of power on a host side by a host ac control line or an SCSI unit to sequentially execute processing in an order of processing of host termination, processing for cache flush of the disk array, processing of host UPS termination, processing of disk array termination, and processing for termination of disk array UPS. Between the UPSs and the Host and between the UPSs and the disk array, there is provided an interlocking control signal to monitor current states thereof so as to control the respective operations. Resultantly, the host UPS and the disk array UPS have the same configuration for wider usability.

BACKGROUND OF THE INVENTION

The present invention relates to an information storage apparatusincluding a disk array including a disk drive and a cache (volatilememory), a host, an uninterruptible power supply (UPS) for the diskarray, and a UPS for the host and a control method of the same.

In a system configuration of an information storage apparatus includinga disk array including a disk drive and a cache, a host, a UPS for thedisk array, and a UPS for the host, when a power failure occurs, thereis required, there is required a procedure to guarantee user data asfollows.

Occurrence of Power Failure

{circle around (1+L )} Processing of host termination and cache flush ofthe disk array (to write data of the cache in the disk drive) andsetting of the system to a write-through mode (to inhibit use of thecache).

{circle around (2)} Recognition of completion of host termination

{circle around (3)} Processing of host UPS termination

{circle around (4)} Processing of disk array termination

{circle around (5)} Recognition of completion of disk array termination

{circle around (6)} Processing of termination of disk array UPS.

JP-A-8-297530 describes a technology related to the operations above.

In accordance with the technology of the publication above, onlyprocessing on the host side of {circle around (1)} and operations of{circle around (2)} and {circle around (3)} can be automaticallyaccomplished. However, the processing on the disk array side of {circlearound (1)} and operations of {circle around (4)} to {circle around (6)}are disadvantageously required to be carried out by human power. Thatis, when a power failure occurs on the host side, only the terminationprocessing is required to be immediately executed; whereas, on the diskarray side, the termination processing is carried out only after data ofthe host side are entirely received. Therefore, the termination must beachieved after the completion of the host termination is recognized andthis restriction results in a difficulty.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide aninterlock control method for each of the operations of {circle around(4)} to {circle around (6)} between the host, the disk array, and theuninterruptible power supplies to thereby automatically conduct theoverall operations including the operation on the disk array side of{circle around (1)} without any intervention of human power so as toguarantee user data.

Furthermore, another object of the present invention is to provide aninterlock control method for wider usability in which the operationbetween the disk array and the UPS and that between the host and the UPSare related to each other in the same control method. Consequently, itis possible to control the disk array and the host by the UPSs of thesame configuration.

To achieve the objects above in accordance with the present invention,there is provided a method as follows.

The uninterruptible power supplies monitor a state change of thehost-side power from on to off to sequentially execute processing in anorder of the processing of host termination, cache flush processing ofthe disk array, the processing of host UPS termination, the processingof disk array termination, and the processing of disk array UPStermination.

Additionally, between the host UPS and the host and between the diskarray UPS and the disk array, there is provided an interlock controlsignal to monitor the respective current states so as to mutuallycontrol respective operations. Consequently, the host UPS and the diskarray UPS advantageously have the same configuration for widerusability.

Moreover, a single UPS to supply power to the disk array and to the hostmonitors the state change of the power on the host side from on to offby a small computer systems interface (SCSI) interface (I/F) or unitestablishing a connection between the host and the disk array tosequentially accomplish processing in an order of the processing of hosttermination, the processing of cache flush of the disk array, theprocessing of disk array termination, and the processing of UPStermination.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become moreapparent from the consideration of the following detailed descriptiontaken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagram schematically showing an overall construction of anembodiment in accordance with the present invention;

FIG. 2 is a diagram showing connections of interlock control signalsbetween a UPS and the host and between a UPS and the disk array;

FIG. 3 is a flowchart showing a procedure of the host UPS and the diskarray UPS at a power failure; and

FIG. 4 is a diagram showing a configuration of another embodiment inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1 to 3, description will be given of anembodiment in accordance with the present invention. FIG. 1 shows anoverall configuration of an embodiment of the present invention.

FIG. 1 shows the various components labeled a, b, and c. The componentslabeled (a) relate to Host (1) and UPS (1), the components labeled (b)relate to Host (2) and UPS (2) and the components labeled (c) relate tothe disk array. However, for ease of illustration, the followingdiscussion may generically refer to the components.

The configuration of the embodiment includes an uninterruptible powersupply (to be referred to as UPS herebelow) (UPS {circle around (1)} andUPS {circle around (2)}) 101, a disk array UPS (UPS {circle around (3)})102, at least one host 103, and at least one disk array 104. The hostUPS 101 and the disk array UPS 102 each include an alternating current(ac) input line 105 and respectively supply power to the host 103 andthe disk array 104 via Ac supply lines 106, respectively. Moreover,between the host UPS 101 and the host 103 and between the disk array UPS102 and the disk array 104, there is provided an interlock controlsignal 107 to control operation therebetween. However, the disk arrayUPS 102 is connected to two disk arrays {circle around (1)} 104 and{circle around (2)} 104 respectively via a port {circle around (1)} anda port {circle around (2)} and hence there are employed two controlsignals, i.e., control {circle around (1)} and control {circle around(2)}.

Moreover, in order for either one of the disk array UPS 102 and the diskarray 104 to monitor a state of power of the host 103, there areprovided two means. One means is a host ac monitor line 108, which alsoincludes a line from the UPS {circle around (1)} and a line from the UPS{circle around (2)} for discrimination between two host UPSs 101, i.e.,UPS {circle around (1)} and UPS {circle around (2)}. The other means isan SCSI I/F or unit 109 connecting the host 103 to the disk array 104,which also includes a line from the host {circle around (1)} and a linefrom the host {circle around (2)}.

In this connection, the present embodiment includes two means of thehost ac monitor line 108 and the SCSI I/F 109. However, the operationabove can also be achieved by using at least either one thereof.

In this embodiment, there are utilized as an example two hosts 103, twodisk arrays 104, and three UPSs, i.e., UPSs 101 and 102. Three UPSs,i.e., UPSs 101 and 102 are of the same internal configuration and arealso the same with each other in external connection modes. Therefore,the UPSs can be connected to the host 1 as well as to the disk array104, namely, the configuration of the UPSs leads to wider usability.However, even when there is employed a UPS 101 including only onecontrol port, there occurs no problem from a viewpoint of the interlockcontrol.

Description will now be given of functions of the UPSs 101 and 102 andthe connection lines thereof. In the UPS 101 and 102, each of the portsis set to the host 103, the disk array 104, or to a disable state. Forexample, in the UPS {circle around (1)}, a host setting is conducted toconnect a port {circle around (1)} control {circle around (1)} to thehost {circle around (1)}. The ac input line occupies one port and isused for the host and disk array UPSs.

The host monitor line 108 is an input line which occupies two ports andwhich monitors the power state of the ac line of the host 103 toestablish a chance of initiation of a planned or programmed terminationof the disk array, and only a voltage of the line is assumed to bemonitored (when the disk array 104 including the disk drive and the datacache is to be stopped or terminated, it is essential to conduct a cacheflush to write dirty data of the cache memory on a disk (not shown) ofthe disk array 104. Therefore, when the apparatus is to be stopped,there is required a sequence in which the cache flush is completed andthen the power of the apparatus is turned off. The procedure toautomatically accomplish the sequence is called “planned or programmedtermination”.)

However, each line has a function of “Disable” (not connected (NC)). Ina case in which the port is set to a host and the host ac monitor line108 is set to Disable, when there is detected a voltage of the ac inputwhich is equal to or less than a predetermined voltage for a period oftime equal to or more than a predetermined period of time, there isunconditionally started processing of a shutdown (programmedtermination) by an interlock control signal. In any other cases, whenthe port detects a voltage which is equal to or less than thepredetermined voltage for a period of time equal to or more than apredetermined period of time, there is started processing of a shutdown(programmed termination) for the disk array 104 connected to the port.Additionally, the ac supply line 106 occupies two ports and serves as apower output line for each of the host UPS 101 and the disk array UPS102 and is controlled by the host ac monitor line 108 and the interlockcontrol signal 107.

Furthermore, the interlock control signal 107 occupies two ports and thehost UPS 101 and the disk array UPS 102 respectively have functions tonotify a chance of initiation of the shutdown processing (programmedtermination) respectively to the host 103 and the disk array 104 andfunctions to recognize completion of the shutdown processing (programmedtermination) of each of the host 103 and the disk array 104.

Additionally, when the port setting is conducted for the disk array 104,the signal 107 has a function to supply a chance for the cache flush andthe write-through mode. This interlock control signal includes afunction to detect a state of a terminator power signal in the SCSI I/F109. Details of the interlock control signal 107 will be described byreferring to FIG. 2.

Next, description will be given of an outline of procedure automationranging from an occurrence of power failure to the processing oftermination of the disk array UPS 102.

Occurrence of power failure

{circle around (1)} Processing for termination of the host 103 (host{circle around (1)} and host {circle around (2)}), the cache flush ofthe disk array 104, and transfer of control to the write-through mode.

{circle around (2)} Recognition of completion of termination of the host103 (hosts {circle around (1)} and {circle around (2)}).

{circle around (3)} Processing for termination of the host UPS 101 (UPSs{circle around (1)} and {circle around (2)}).

{circle around (4)} Processing for termination of the disk array 104(disk arrays {circle around (1)} and {circle around (2)}).

{circle around (5)} Recognition of completion of termination of the diskarray 104 (disk arrays {circle around (1)} and {circle around (2)}).

{circle around (6)} Processing for termination of the disk array UPS 102(UPS {circle around (3)}).

Procedure {circle around (1)}

When a power failure occurs, the port {circle around (1)} of the UPS 101(UPSs {circle around (1)} and {circle around (2)}) of the host settingunconditionally initiates shutdown processing of the host 103 (hosts{circle around (1)} and {circle around (1)}) by an interlock controlsignal. Details of the interlock control will also be described later inconjunction with explanation of FIG. 2.

On the other hand, for the ports {circle around (1)} and {circle around(2)} of the UPS 102 (UPS {circle around (3)}) of which the host acmonitor line 108 is set to Enable, since both of the lines of the hostac monitor line 108, i.e., a line to the UPS {circle around (1)} and aline to the UPS {circle around (2)} are powered, the cache flush and thewrite-through mode are initiated.

Procedure {circle around (2)}

When the shutdown processing is completed, the host 103 (hosts {circlearound (1)} and {circle around (2)}) immediately reports the completionof host termination to the UPS 101 (UPSs {circle around (1)} and {circlearound (1)}) by an interlock control signal.

Procedure {circle around (3)}

On receiving a report of completion of the host termination from thehost 103 (hosts ({circle around (1)} and {circle around (2)}), the UPS101 (UPS {circle around (1)} and UPS {circle around (2)})is stopped.

Procedure {circle around (4)}

When a voltage which is equal to or less than a predetermined voltageand which continues for a period of time equal to or more than apredetermined period of time is recognized in both of the power sourcesof the host ac monitor line 108, i.e., ac {circle around (1)} connectedto the UPS {circle around (1)} and ac {circle around (2)} connected tothe UPS {circle around (2)} or when a terminator power of the SCSI I/F109 including means capable of recognizing the completion of hosttermination is interrupted, the interlock control signal 107 initiatesthe shutdown processing (programmed termination) of the disk array 104(disk array {circle around (1)} and disk array {circle around (2)}). Inthis case, it is only necessary to use the host ac monitor line 108 orthe terminator power of the SCSI I/F 109. However, the selection forutilization thereof depends on the Enable or Disable setting for the acmonitor line 108 and TRM POWER-N, which will be described later.

Procedure {circle around (5)}

When the programmed termination is completed, the disk array (diskarrays {circle around (1)} and {circle around (2)}) immediately reportsby the interlock control signal 107 the completion of disk arraytermination to the UPS 102 (UPS {circle around (3)}).

Procedure {circle around (6)}

On receiving a report of the completion of disk array termination fromthe disk arrays 104 at both ports (disk arrays {circle around (1)} and{circle around (2)}), the UPS 102 (UPS {circle around (3)}) terminatesits own operation.

Subsequently, description will be given in detail of the interlockcontrol between the UPS and the host or between the UPS and the diskarray. FIG. 2 shows connections of interlock control signals 201 to 209between the UPSs 101 and 102 (UPS 200 in this diagram) and the host 103(host 210 in this diagram) as well as the disk array 104 (disk array 220in this diagram) shown in FIG. 1. In this diagram, numerals 201 to 203indicate control signals between the host 210 or the disk array 220 andthe UPS 200, numerals 204 to 207 designate status signals, and numerals208 and 209 respectively indicate a power source and a groundingpotential.

“CAFLUSH-N” 201 is a signal outputted from the UPS 200 to request thedisk array 220 for the cache flush and the state transition to thewrite-through mode. “OFFREQ-N” 202 is a signal outputted from the UPS200 to request the host 210 or the disk array 220 to turn power off.Moreover, “OFFOK-N” 203 is an input signal to the UPS 200 and indicatesthat the host 210 or the disk array 220 stops the processing oftermination. The signal 203 permits the UPS 200 to turn power off. Whenan OFFOK signal is inputted to each port in the Enable state, the UPS200 immediately turns power off regardless of the state ofCAFLUSH/OFFREQ.

In addition, “TRM POWER-N” 204 is a signal inputted to the UPS 200. Thissignal is an OR signal obtained by ORing all signals of the terminatorpower line of SCSI.

However, the signal 204 has a “disable” function. In an interlockcontrol mode related to the SCSI terminator power line, when this signalis used to start supplying power to the ac supply line of the UPS 200,the UPS 200 must not monitor the signal line thereafter. In other words,when this signal is negated after the power supplying operation isstarted, the ac supply line is kept retained. The ac supply line isinterrupted only in response to assertion of OFFOK.

Furthermore, “Power SW-OFF-N” 205 is an input signal to the UPS 200 andindicates that a main switch of the host 210 or the disk array 220 ison. “Cable OK1-N” 206 is an input signal to the UPS 200, and this signalline is connected to a ground potential (GND) in the host 210 or thedisk array 220. The UPS 200 raises the voltage of the signal line. Whenthis signal is at a Low level, the UPS 200 recognizes normality of cableconnection. Additionally, “Cable OK2-N” 207 is an output signal from theUPS 200 and its signal line is connected to a ground potential (GND) inthe host 210 or the disk array 220. The UPS 200 increases a potential ofthe signal line. When the signal is at a Low level, the UPS 200recognizes normality of cable connection.

Moreover, “Vcc” 208 as the power source is outputted from the UPS 200and is continuously supplied to the host or the disk array. “GND” 209 isa ground (GND) signal for the ground potential.

FIG. 3 shows a flow of procedures of the UPSs 101 and 102 respectivelyon the side of host 103 and on the side of disk array 104 a t powerfailure. When a power failure occurs, each port of the host UPS 101 andthe disk array UPS 102 recognizes that the port is connected to the host103 or the disk array 104 in accordance with the port setting of eachUPS (UPSs {circle around (1)}, {circle around (2)}, and {circle around(3)} of FIG. 1 are indicated as the host setting, the host setting, andthe disk array setting, respectively).

The host UPS 101 immediately issues “OFFREQ-N” 202 to the host to startthe shutdown processing of the host 103 (this corresponds to theprocedure {circle around (1)} after occurrence of the power failureabove). When “OFFK-N” 203 indicating the termination of shutdownprocessing is received from the host 103 (procedure {circle around(2)}), the operation of the host UPS 101 is terminated (procedure{circle around (3)}).

The disk array UPS 102 monitors the host ac monitor line 108 or “TRMPOWER-N” 204 to recognize the termination of the host UPS 101 or thehost 103 itself. At recognition of the termination, the shutdownprocessing (programmed termination) of the disk array 104 is started(procedure {circle around (4)}). As in the case of the host UPS 101,when “OFFOK-N” 203 indicating the completion of the programmedtermination is received from all disk arrays 104 connected to the ports(procedure {circle around (5)}), the operation of disk array UPS 102 isterminated (procedure {circle around (6)}).

FIG. 4 is a diagram showing a configuration of another embodiment inaccordance with the present invention. In the configuration of thisembodiment, only one UPS 401 is employed for the host and the diskarray. The UPS 401 includes an ac input line 404 to supply power via acsupply lines 405 respectively to a host 402 (corresponding to the host103 of FIG. 1) and a disk array 403. Moreover, between the UPS 401 andthe host 402 and between the UPS 401 and the disk array 403, there isused an interlock control signal 406 to control operation therebetween.The host setting and the disk array setting are specified respectivelyfor the side of port 1 and the side of port 2, which are connected tothe host 402 and the disk array 403, respectively.

The host ac monitor line 407 is set to Disable such that the state ofpower of the host 402 is monitored by an SCSI I/F 408. The interlockcontrol is basically the same as for the embodiment described above.However, this embodiment varies from the embodiment above only in thatbecause the UPS 401 is connected not only to the host 402 but also tothe disk array. That is, after the host 402 conducts the shutdownprocessing, process goes to the processing to terminate the operation ofdisk array 403 (procedure {circle around (4)}) without executing theprocessing to stop the UPS 401 (procedure {circle around (3)}).

As described above, in accordance with the embodiments of the presentinvention, there are provided an interlock control method using signalsto monitor various states between the host and the UPS and between thedisk array and the UPS so as to control operation therebetween, afunction for the disk array to recognize the state of power of the hostby an existing SCSI I/F signal, and/or a function for the disk array UPSto recognize the power state of the host by sending a host ac linesignal of the host UPS to the disk array UPS. Consequently, it ispossible to automatically execute all processing of {circle around (1)}to {circle around (6)} after a power failure.

Furthermore, since the host, the disk array, and the UPSs areinterlockingly controlled, a sequence of operations including theinitiation of the shutdown processing of the host at power failure, theshutdown processing (programmed termination) of the disk array after theshutdown of the host, and the power off processing of the UPS can beautomatically conducted without any intervention of human power tothereby guarantee user data.

In addition, since operation between the disk array and the UPS andoperation between the host and the UPS are interlockingly controlled inthe same control method, it is possible to control both of the diskarray and the host by the same UPS. This advantageously results in aninterlock control method with wider usability for more generalized uses.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by thoseembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

What is claimed is:
 1. An information storage apparatus, comprising: adisk array including a disk drive and a data cache; a host connected tothe disk array; a disk array uninterruptible power supply (UPS) forsupplying power to the disk array; a host UPS for supplying power to thehost; and a monitor line for monitoring a change of a state of the powerof the host from on to off.
 2. An information storage apparatus inaccordance with claim 1, wherein the monitor line is a small computersystems interface (SCSI) unit to connect the host to the disk array. 3.An information storage apparatus according to claim 2, wherein themonitor line monitors the change of the state of the power of the hostfrom an on-state to an off-state based on terminator power of a SCSIinterface.
 4. An information storage apparatus in accordance with claim1, wherein the monitor line is a host alternating current (ac) monitorline to connect the host UPS to the disk array UPS.
 5. An informationstorage apparatus in accordance with claim 1, wherein: the monitor lineincludes a host ac monitor line to connect the host UPS to the diskarray UPS and an SCSI unit to connect the host to the disk array.
 6. Aninformation storage apparatus in accordance with claim 1, furtherincluding an interlocking control signal between the host UPS and thehost and between the disk array UPS and the disk array for respectivelymonitoring current states therebetween and respectively controllingoperations therebetween.
 7. An information storage apparatus inaccordance with claim 1, wherein said host UPS is separate from saiddisk array UPS.
 8. An information storage apparatus, comprising: a diskarray including a disk drive and a data cache; a host connected to thedisk array; a UPS for supplying power to the disk array and the host;and an SCSI unit for monitoring a change of a state of the power of thehost from on to off, the SCSI unit connecting the host to the diskarray.
 9. An information storage apparatus according to claim 8, whereinthe SCSI unit monitors the change of the state of the power of the hostfrom an on-state to an off-state based on terminator power of a SCSIinterface.
 10. An interlocking control method for use in an informationstorage apparatus including a disk array including a disk drive and adata cache, a host connect to the disk array, a host UPS for supplyingpower to the host, and a disk array UPS for supplying power to the diskarray, comprising the following steps of: monitoring by each of the UPSsa change of a state of the power on a side of the host from on to off;terminating the host by the host UPS; flushing the cache of the diskarray by the disk array UPS; terminating the host UPS by the host UPS;and terminating the disk array and the disk array UPS by the disk arrayUPS.
 11. An interlocking control method in accordance with claim 10,wherein the step of monitoring a change of a state of the power on aside of the host from on to off is conducted by an SCSI unit connectingthe host to the disk array.
 12. An interlocking control method accordingto claim 11, wherein the step of monitoring includes a substep ofmonitoring the change of the state of the power on the side of the hostfrom an on-state to an off-state based on terminator power of a SCSIinterface.
 13. An interlocking control method in accordance with claim10, wherein the step of monitoring a change of a state the power on aside of the host from on to off is conducted by a host ac monitor lineof the host UPS.
 14. An interlocking control method in accordance withclaim 10, wherein the step of monitoring a change of a state of thepower on a side of the host from on to off is conducted by a host acmonitor line of the host UPS and an SCSI unit connecting the host to thedisk array.
 15. An interlocking control method in accordance with claim10, wherein said host UPS is separate from said disk array UPS.